Appearance inspection device for die-casting product

Abstract

The present invention addresses the problem of suppressing the occurrence of halo in a captured image even when an illumination unit is used for direct illumination in order to avoid an increase in the size of the entire device. The inspection device includes: a plurality of rod-shaped illuminators that irradiate illumination light from the surroundings to the die-casting product placed on the stage; a robot arm for sequentially moving the first camera to a plurality of imaging points so as to image different parts of the die-casting product on the stage; a storage device that stores a first dimming value that is set for each imaging point such that halo does not occur in the captured image; and a controller for controlling the amount of illumination light from the rod-type illumination on the basis of the corresponding first dimming value in a state where the first camera is located at each imaging point, and then causing the first camera to image the die-cast product.

Description

Technical Field

[0001] This invention relates to a device for visual inspection of die-cast products. Background Technology

[0002] The document describes a nesting tendency management device that photographs the surface features of a casting illuminated by a lighting device, processes the photographed images to quantify the amount of recesses in the surface features, and estimates the amount of nesting based on the relationship between the amount of recesses and the amount of nesting inside the casting.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2016-68100 Summary of the Invention

[0004] When using a camera to inspect the appearance of die-cast products, it is required to illuminate the product surface evenly (in a way that avoids halos and eliminates areas of insufficient brightness). Therefore, indirect lighting is often used as the lighting device. However, when the product being inspected is a one-piece die-cast product, the product becomes large and its shape becomes complex. Therefore, if an indirect lighting device is used, the illumination distance from the light source to the product becomes longer, resulting in insufficient light due to attenuation, and the overall device becomes larger. Furthermore, if a direct lighting device is used, there is a problem of halos appearing in the captured images.

[0005] The present invention was made in view of the above facts, and its object is to obtain an appearance inspection device for die-cast products that can suppress the generation of halos in the photographic images even when a configuration for direct illumination is adopted to avoid the overall large size of the device.

[0006] The appearance inspection device for die-cast products according to the first method includes: a first illumination unit that illuminates the die-cast product placed on a mounting platform from the surroundings; a moving unit that sequentially moves the camera unit to multiple camera points to capture images of different parts of the die-cast product on the mounting platform; a storage unit that stores a first dimming value set for each camera point to prevent halos in the captured image; and a control unit that, when the camera unit is located at each camera point, controls the amount of illumination light from the first illumination unit based on the corresponding first dimming value stored in the storage unit, and then causes the camera unit to capture images of the die-cast product.

[0007] In the first method, a first dimming value is determined for each camera point of the camera unit to prevent halos in the captured image. Furthermore, with the camera unit positioned at each camera point, the control unit controls the amount of illumination light from the first illumination unit according to the corresponding first dimming value before the camera unit captures the die-cast product. Thus, in the first method, the amount of illumination light from the first illumination unit is controlled for each camera point to prevent halos in the captured image. Therefore, even when a configuration is adopted where the first illumination unit provides direct illumination to avoid increasing the overall size of the device, halos in the captured image can be suppressed.

[0008] The second method, in addition to the first method, further includes: a second illumination unit, which is moved to each camera point together with the camera unit via the moving unit; as the dimming value of the second illumination unit at a specific camera point for photographing the recess of the die-cast product, the storage unit stores a plurality of second dimming values, which are respectively set such that no halo is generated in the areas corresponding to different parts of the recess in the photographed image; when the camera unit and the second illumination unit are located at the specific camera point, the control unit uses each of the plurality of second dimming values ​​to control the amount of illumination light from the second illumination unit, and causes the camera unit to take multiple photographs of the recess.

[0009] For example, when the die-cast product being inspected is a one-piece die-cast product, the shape becomes complex, and the opening area or depth of the recesses on the surface increases. Therefore, the illumination light from the first illumination unit may not reach the recesses sufficiently, resulting in uneven brightness within the recesses. In contrast, the second method includes a second illumination unit that is moved to each camera point along with the camera unit. Furthermore, multiple second dimming values ​​are determined as dimming values ​​for the second illumination unit at specific camera points for photographing the recesses of the die-cast product, such that areas corresponding to different parts within the recesses in the photographed image do not produce halos. Moreover, with the camera unit and the second illumination unit positioned at the specific camera points, the control unit repeatedly controls the amount of illumination light from the second illumination unit using each of the multiple second dimming values, and causes the camera unit to photograph the recesses. Thus, through multiple photographs at specific camera points, multiple images of different parts within the recesses can be obtained, allowing for appropriate photographing of each part within the product's recesses.

[0010] In the third method, the plurality of second dimming values ​​are set to prevent halo effects in the area corresponding to the bottom of the recess in the image, and to prevent halo effects in the area corresponding to the side of the recess in the image.

[0011] In the recesses of die-cast products, the appropriate amount of illumination often differs significantly, especially between the bottom and sides of the recess. In contrast, in the third method, multiple second dimming values ​​are set to determine whether a halo effect is produced in the area corresponding to the bottom of the recess in the captured image, and whether a halo effect is produced in the area corresponding to the side of the recess in the captured image. Thus, by taking two shots at a specific shooting point, images of the bottom and side of the recess that are appropriately captured can be obtained, reducing the number of shots required.

[0012] The fourth method is the same as the first method, where the die-cast product is an integrated die-cast product manufactured by integrated die casting.

[0013] According to the fourth method, it is possible to properly photograph various parts of a large and complex integrated die-cast product without producing a halo effect.

[0014] Invention Effects

[0015] The present invention has the effect of suppressing the generation of halos in the photographic images even when a configuration for direct illumination is adopted in order to avoid the overall large size of the device. Attached Figure Description

[0016] Figure 1 This is a block diagram showing the general structure of the appearance inspection device for die-cast products according to the embodiment.

[0017] Figure 2 It is a 3D diagram representing a robot arm, rod-shaped lighting, etc.

[0018] Figure 3 This is a side view showing the configuration of the front end of the robot arm.

[0019] Figure 4 The diagram shows the state of the ring light being brought close to the recess of the product. (A) is a perspective view, and (B) is a side view.

[0020] Figure 5 This is a chart representing an example of a camera point / lighting light quantity table.

[0021] Figure 6 This is a flowchart illustrating an example of lighting / camera control processing performed by a controller. Detailed Implementation

[0022] Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Figure 1The image shows a die-cast product appearance inspection device 10 (hereinafter simply referred to as "inspection device 10") according to this embodiment. The inspection device 10 takes pictures of the die-cast product 60 (one example shown) from multiple different camera points. Figure 4 The device for determining whether there are defects on the surface of the die-cast product 60 based on the camera images includes a robotic arm 12, a first camera 16, and a controller 28.

[0023] In addition, the die-cast product 60 that the inspection device 10 inspects can be, for example, an integrated die-cast product such as a vehicle frame in which the wheel arches and side longitudinal beams are integrally formed by Gipa casting, or a typical die-cast product such as a transmission drive axle housing.

[0024] like Figure 2 As shown, the robotic arm 12 is composed of a vertical multi-joint robot, including multiple actuators 14 for moving each joint, and is connected to a controller 28. The robotic arm 12 is positioned near the stage 50 on which the die-cast product 60 to be inspected is placed, and a first camera 16 is mounted at its front end (see reference). Figure 3 According to instructions from the controller 28, the front end of the robot arm 12, namely the first camera 16 (and the second camera 22 and the ring illumination 24 described later), is moved sequentially to a plurality of pre-set camera points. The robot arm 12 is an example of a moving part in the present invention, and the platform 50 is an example of a mounting platform in the present invention.

[0025] The first camera 16 is connected to the controller 28, which controls it to photograph the die-cast product 60 on the stage 50 each time the robot arm 12 moves to various camera points. The images obtained by the first camera 16 are output to the controller 28. Furthermore, the first camera 16 is a wide-angle camera capable of capturing a wider range than the second camera 22 described later. The first camera 16 is an example of the camera unit in this invention.

[0026] And, as Figure 2 As shown, a frame 52 is provided around the stage 50 to surround the stage 50 and the robot arm 12, and multiple rod-shaped lights 18 are mounted on the frame 52. When illuminated, the multiple rod-shaped lights 18 illuminate the die-cast product 60, the object to be inspected, placed on the stage 50. Furthermore, the multiple rod-shaped lights 18 are connected to the controller 28 via the lighting controller 20. Alternatively, the rod-shaped lights 18 can illuminate the structure of the die-cast product 60 using either indirect or direct light.

[0027] In this embodiment, when the first camera 16 takes pictures at each camera point, a first dimming value is determined for each camera point and for each bar illuminator 18 to prevent halos from appearing in the captured image. The amount of illumination light from each of the multiple bar illuminators 18 is individually controlled according to the first dimming value each time the first camera 16 moves to a different camera point. The multiple bar illuminators 18 are an example of the first illumination unit in this invention.

[0028] Furthermore, a recess 62 for illuminating the surface depressions in the die-cast product 60 is connected to the controller 28 via the lighting controller 26 (an example is shown). Figure 4 (B)) includes a ring-shaped lighting 24, and is connected to a second camera 22 for illuminating the recess 62. (See example) Figure 3 As shown, the second camera 22 and the ring-shaped illumination 24 are mounted coaxially with the front end of the robot arm 12, and together with the first camera 16, are moved sequentially to each imaging point via the robot arm 12. The ring-shaped illumination 24 is an example of the second illumination unit in this invention, and the second camera 22 is also an example of the imaging unit in this invention.

[0029] In this embodiment, among the multiple camera points is a specific camera point positioned near the recess 62 for photographing the interior of the die-cast product 60. Additionally, Figure 4 (A) and (B) show an example of the state of the second camera 22 and the ring illumination 24 at a specific camera point.

[0030] Furthermore, in this embodiment, for specific camera points within the recess 62 used for imaging, a bottom 62A (see reference) is provided within the recess 62. Figure 4 (B) Using the second dimming value and the side portion 62B inside the recess 62 (reference) Figure 4 (B) Using the second dimming value. The bottom 62A within the recess 62 is determined by the second dimming value to be an area in the captured image corresponding to the bottom 62A within the recess 62 that does not produce a halo. Furthermore, the side 62B within the recess 62 is determined by the second dimming value by the second camera 22 to be an area in the captured image corresponding to the side 62B within the recess 62 that does not produce a halo.

[0031] The ring-shaped illumination 24 is activated by the controller 28 when the robot arm 12 moves to a specific camera point. Furthermore, the ring-shaped illumination 24 undergoes two-stage dimming: first, the amount of illumination light is controlled using a second dimming value based on the bottom 62A within the recess 62; then, the amount of illumination light is controlled using a second dimming value based on the side 62B within the recess 62. The second camera 22 is controlled by the controller 28 to capture images of the recess 62 in two states: a first state where the ring-shaped illumination 24 is dimmed for the bottom 62A within the recess 62, and a second state where the ring-shaped illumination 24 is dimmed for the side 62B within the recess 62. The captured images obtained by the second camera 22 are output to the controller 28.

[0032] The controller 28 includes a central processing unit (CPU) 30, a read-only memory (ROM) 32, a random access memory (RAM) 34, a storage device 36 such as a hard disk drive (HDD) or a solid state drive (SSD), an interface (I / F) 38, and input / output (I / F) 40, which are interconnected via a bus 42.

[0033] The storage device 36 stores a camera point / illumination light level meter 44. For example... Figure 5 As shown, the camera point / lighting meter 44 records camera point information for moving the front end of the robot arm 12 to each camera point and a two-stage dimming flag indicating whether each camera point performs two-stage dimming to capture a specific camera point within the recess 62. Furthermore, the camera point / lighting meter 44 records a first dimming value for each rod-shaped illumination 18 for a normal camera point where the two-stage dimming flag is set to 0. Moreover, the camera point / lighting meter 44 records a second dimming value for the bottom and a second dimming value for the side of the ring-shaped illumination 24 for a specific camera point where the two-stage dimming flag is set to 1.

[0034] Furthermore, in this embodiment, the first dimming value registered in the camera point / illumination light level table 44 is set as follows: While moving the first camera 16 to a normal camera point, the first camera 16 is used to photograph the die-cast product 60 while multiple bar lights 18 are illuminated at predetermined dimming values. Next, the operator observes the inspection area corresponding to the inspection target of the die-cast product 60 in the image obtained by the first camera 16, and determines whether a halo is generated in the inspection area and whether the brightness of the inspection area is sufficient. If a halo is generated in the inspection area, the illumination light level of the specific bar lights 18 illuminating the inspection target area is reduced; conversely, if the brightness of the inspection area is insufficient, the illumination light level of the specific bar lights 18 is increased, and the first camera 16 re-photographs. Furthermore, the dimming value of each bar light 18 when it is determined that no halo is generated in the inspection area and the brightness of the inspection area is sufficient is saved as the first dimming value corresponding to the current camera point. By performing the above operations sequentially for the usual camera points, the first dimming value for each camera point and each bar lighting 18 is obtained.

[0035] Furthermore, in this embodiment, the second dimming value registered in the camera point / illumination light level table 44 is set as follows: That is, while moving the second camera 22 to a specific camera point, the ring illumination 24 is lit at a predetermined dimming value, and the second camera 22 captures an image of the recess 62 of the die-cast product 60. Next, the operator observes the inspection area corresponding to the bottom of the recess 62 of the die-cast product 60 in the image obtained by the second camera 22, and determines whether a halo is generated in the inspection area and whether the brightness of the inspection area is sufficient. If a halo is generated in the inspection area, the illumination light from the ring illumination 24 is reduced; conversely, if the brightness of the inspection area is insufficient, the illumination light from the ring illumination 24 is increased, and the second camera 22 re-captures the image. Furthermore, the dimming value of the ring illumination 24 when it is determined that no halo is generated in the inspection area and the brightness of the inspection area is sufficient is saved as the second dimming value for the bottom of the recess 62 corresponding to the current specific camera point.

[0036] Next, with the ring illumination 24 lit at a predetermined dimming value, the second camera 22 captures an image of the recess 62 of the die-cast product 60. The operator then observes the inspection area corresponding to the side portion of the recess 62 in the image obtained from the second camera 22, determining whether a halo effect occurs in the inspection area and whether the brightness of the inspection area is sufficient. If a halo effect occurs in the inspection area, the illumination intensity from the ring illumination 24 is reduced; conversely, if the brightness of the inspection area is insufficient, the illumination intensity from the ring illumination 24 is increased, and the second camera 22 re-captures the image. Furthermore, the dimming value of the ring illumination 24, determined to be in a state where no halo effect occurs in the inspection area and the brightness of the inspection area is sufficient, is saved as the second dimming value for the side portion of the recess 62 corresponding to the current specific camera point.

[0037] Furthermore, a defect inspection device 46 is connected to the controller 28, and images captured by the first camera 16 or the second camera 22 are sent from the controller 28 to the defect inspection device 46. The defect inspection device 46 uses artificial intelligence (AI) that has been pre-learned to capture multiple defect images of areas where defects appear on the surface of the die-cast product 60 to determine whether a defect exists in the image received from the controller 28. Alternatively, a bypass circuit can be provided that directly connects the first camera 16 and the second camera 22 to the defect inspection device 46, so that images captured by the first camera 16 or the second camera 22 are sent directly to the defect inspection device 46 without going through the controller 28.

[0038] Next, as for the purpose of this embodiment, refer to Figure 6 The lighting / camera control process performed by the controller 28 during the inspection of the die-cast product 60 will be described. In step 100 of the lighting / camera control process, the controller 28 reads the camera point information registered in position 1 of the camera point / light intensity table 44. Furthermore, by driving the actuator 14 according to the read camera point information, the front end of the robot arm 12 is moved to the camera point corresponding to the read camera point information.

[0039] In step 102, the controller 28 determines whether the current camera point (the current camera point) at the front end of the robot arm 12 is a specific camera point within the recess 62 that requires two-stage dimming to capture the image. This determination in step 102 can be achieved, for example, by checking whether the dimming flags for the two stages corresponding to the camera point information read in step 100 are set to 1.

[0040] If the determination in step 102 is rejected, the process proceeds to step 104, where the controller 28 reads the first dimming value corresponding to the current camera point from the camera point / illumination light level meter 44. Furthermore, in step 106, the controller 28 controls each of the bar-shaped lights 18 via the illumination controller 20 so that the amount of illumination light from each of the bar-shaped lights 18 corresponds to the amount of light read in step 104. Then, in step 108, the controller 28 causes the first camera 16 to capture an image of the die-cast product 60. Finally, in step 110, the controller 28 sends the image captured by the first camera 16 to the defect inspection device 46, and the process proceeds to step 126.

[0041] Furthermore, if the determination in step 102 is affirmative, the process proceeds to step 112. In step 112, the controller 28 reads the second dimming value for the bottom 62A within the recess 62 corresponding to the current camera point from the camera point / illumination light level meter 44. In step 114, the controller 28 controls the ring illumination 24 via the illumination controller 26 to make the amount of illumination light emitted from the ring illumination 24 correspond to the amount of light for the bottom 62A using the second dimming value. Moreover, in step 116, the controller 28 causes the second camera 22 to capture an image of the recess 62 within the die-cast product 60. In this capture in step 116, the image is captured in such a way that the area corresponding to the bottom 62A within the recess 62 in the captured image has appropriate brightness. In step 117, the controller 28 sends the captured image of the recess 62 captured in step 116 to the defect inspection device 46. In addition, in the defect inspection device 46 that receives the camera image, the area in the image captured in step 116 corresponding to the bottom 62A in the recess 62 is inspected for defects.

[0042] Furthermore, in the next step 118, the controller 28 reads the second dimming value for the side portion 62B within the recess 62 corresponding to the current camera point from the camera point / illumination light level meter 44. In step 120, the controller 28 controls the ring illumination 24 via the illumination controller 26 to make the amount of illumination light from the ring illumination 24 correspond to the amount of light for the side portion 62B using the second dimming value. Furthermore, in step 122, the controller 28 causes the second camera 22 to capture an image of the recess 62 within the die-cast product 60. In this step 122, the image is captured in such a way that the area corresponding to the side portion 62B within the recess 62 in the captured image has appropriate brightness.

[0043] Furthermore, in step 124, the controller 28 sends the camera image of the recess 62 captured in step 122 to the defect inspection device 46, thus transferring to step 126. Additionally, in the defect inspection device 46 that receives the camera image, the area corresponding to the side portion 62B within the recess 62 in the image captured in step 122 is inspected for defects.

[0044] In step 126, the controller 28 determines whether an image has been captured at all camera points registered in the camera point / lighting meter 44. If the determination in step 126 is negative, the process returns to step 100 and repeats steps 100 to 126 until the determination in step 126 is positive. Thus, information registered from the second position onwards in the camera point / lighting meter 44 is read sequentially, and the aforementioned dimming and capturing are performed accordingly. Furthermore, if the determination in step 126 is positive, the lighting / camera control process ends.

[0045] Thus, in this embodiment, the inspection apparatus 10 includes: a plurality of rod-shaped lights 18 that illuminate the die-cast product 60 placed on the stage 50 from the surroundings; a robotic arm 12 that moves a first camera 16 sequentially to a plurality of camera points for photographing different parts of the die-cast product 60 placed on the stage 50; a storage device 36 that determines a first dimming value for each camera point in a manner that prevents halos from appearing in the photographed image; and a controller 28 that, while the first camera 16 is located at each camera point, controls the amount of illumination light from the rod-shaped lights 18 according to the corresponding first dimming value stored in the storage device 36, and then causes the first camera 16 to photograph the die-cast product 60. Therefore, even when a configuration using rod-shaped lights 18 for direct illumination is adopted to avoid increasing the overall size of the inspection apparatus 10, halos can be suppressed in the photographed image.

[0046] Furthermore, in this embodiment, an annular illumination 24, which is moved to each camera point by the robotic arm 12 along with the first camera 16 and the second camera 22, serves as the dimming value for the second illumination portion at a specific camera point used for photographing the recess 62 of the die-cast product 60. A storage device 36 stores multiple second dimming values, each set to prevent halos from appearing in areas corresponding to different portions within the recess 62 in the photographed image. The controller 28, while the second camera 22 and the annular illumination 24 are positioned at the specific camera point, uses each of the multiple second dimming values ​​to control the amount of illumination light from the annular illumination 24 multiple times, and causes the second camera 22 to photograph the recess 62. Thus, through multiple photographs at the specific camera point, multiple images of different portions within the recess 62 can be obtained, allowing for appropriate photographing of each portion within the product's recess.

[0047] Furthermore, in this embodiment, the plurality of second dimming values ​​are second dimming values ​​determined in a manner that prevents halo effects from occurring in the area corresponding to the bottom 62A within the recess 62 in the captured image, and second dimming values ​​determined in a manner that prevents halo effects from occurring in the area corresponding to the side 62B within the recess 62 in the captured image. Thus, by taking two shots at a specific shooting point, it is possible to obtain an image in which the bottom 62A within the recess 62 is appropriately captured and an image in which the side 62B within the recess 62 is appropriately captured, thereby reducing the number of shots required.

[0048] Furthermore, in the above embodiment, the method of setting up a first camera 16 for shooting at a normal shooting point and a second camera 22 for shooting at a specific shooting point (shooting within the recess 62) has been described. However, the present invention is not limited to this, and a single camera capable of changing the shooting angle may also be provided to switch the shooting angle between shooting at a normal shooting point and shooting at a specific shooting point.

[0049] Furthermore, in the above embodiment, the amount of illumination light from the rod-shaped illuminator 18 when shooting at a specific shooting point using the second camera 22 and the ring illuminator 24 is not specifically described. However, depending on the direction or shape of the recess being shot, the amount of illumination light from the rod-shaped illuminator 18 may affect the shooting at that specific shooting point. Taking this into account, it is preferable to determine and store a first dimming value for each specific shooting point, and control the amount of illumination light from the rod-shaped illuminator 18 according to the corresponding first dimming value when shooting at that specific shooting point using the second camera 22 and the ring illuminator 24.

[0050] Furthermore, while the above embodiments describe the controller 28 as being configured as a computer, the present invention is not limited to this, and the controller 28 may also be configured as a programmable logic controller (PLC), for example. Also, while the above embodiments describe the camera point / lighting meter 44 registering camera point information, dimming values, etc., and storing them in the storage device 36 of the controller 28, the present invention is not limited to this. For example, typically, the robot arm 12 has a built-in control unit, and the camera point information, dimming values, etc., may also be stored in a storage device with a built-in control unit.

[0051] Symbol Explanation

[0052] 10-Appearance inspection device for die-cast products, 12-Robot arm (moving part), 16-First camera (image-capturing part), 18-Bar-shaped illumination (first illumination part), 22-Second camera (image-capturing part), 24-Ring-shaped illumination (second illumination part), 28-Controller (control part), 36-Storage device (storage part), 60-Die-cast product, 62-Recess, 62A-Bottom, 62B-Side.

Claims

1. A device for visual inspection of die-cast products, characterized in that, include: The first lighting section illuminates the die-cast product placed on the mounting platform from the surrounding area. The moving part is used to move the camera part sequentially to multiple camera points so as to photograph different parts of the die-cast product on the mounting platform; The storage unit stores the first dimming value set for each camera point to prevent halos in the captured image; and A control unit is configured to, when the camera unit is located at each camera point, control the amount of illumination light from the first illumination unit based on the corresponding first dimming value stored in the storage unit, and then cause the camera unit to capture images of the die-cast product.

2. The appearance inspection device for die-cast products according to claim 1, characterized in that, Also includes: The second lighting unit is moved to each camera point together with the camera unit via the moving unit; As the dimming value of the second illumination part in a specific camera point used to photograph the recess of the die-cast product, the storage part stores a plurality of second dimming values, which are respectively set such that no halo is generated in the areas corresponding to different parts in the recess in the photographed image. When the camera unit and the second illumination unit are located at the specific camera point, the control unit uses each of the plurality of second dimming values ​​to control the amount of illumination light from the second illumination unit, and causes the camera unit to take multiple shots of the recess.

3. The appearance inspection device for die-cast products according to claim 2, characterized in that, The plurality of second dimming values ​​are set to prevent halo effects in the area corresponding to the bottom of the recess in the image, and to prevent halo effects in the area corresponding to the side of the recess in the image.

4. The appearance inspection device for die-cast products according to claim 1, characterized in that, The die-cast product is an integrated die-cast product manufactured through integrated die casting.

Images